Railway signaling



R. A. McCANN.

RAIVLWAEY SIGNALING. APPLICATION FILED JUNE 1, 12m). RENEWED MAY 23, 1917.

1,335,381 Patented Mar. 30, 1920.

INVENTOR WEST UNITED STATES PATENT OFFICE.

RONALD A. McCANN, 0F SWISSVALE, PENNSYLVANIA, ASSIGNOR TO THE UNION SWITCH 85 SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPORA- TION OF PENNSYLVANIA.

RAILWAY SIGNALING.

Application filed June 1, 1916, Serial No. 101,014. Renewed May 23, 1917.

To all whom it may concern:

Be it known that I, RONALD A. MGCANN, a citizen of the United States, residing at Swissvale, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Railway Signaling, of which the following is a specification.

My invention relates to railway signaling, and particularly to signaling for single track roads.

I shall describe one form and arrangement of circuits and apparatus embodying my invention and then point out the novel features thereof in claims.

The accompanying drawing is a diagrammatic view showing one form of circuits and apparatus embodying my invention.

Vith reference to this drawing, AD is a stretch of single track, the track rails 1 and 1 of which are divided into sections by means of insulations 2. In the drawing I have shown only one complete section BC, and parts AB and CD of the two sections adjacent to section BC, but it is understood that there may be any number of similar sections throughout the stretch of track. Each track section is provided with a track circuit which I have shown to be of the center-fed type, although I do not wish to be limited to this particular form of track circuit. The track circuit of section BC (to which section I shall hereinafter limit my description for the sake of simplicity) is supplied with energy from a transformer T which is fed from a transmission line L energized by an alternating current generator 0. The current in this track circuit energizes two track relays R and R located adjacent the ends of the section.

Adjacent each end of each section are located signals S for governing traffic in opposite directions through the stretch; thus sig nal S governs eastbound traflic into section BC and signal S" governs Westbound traffic into section 13-A. The signals S, as here shown, are in the form of light signals capable of displaying three indications,

namely proceed when a green lamp G is illuminated, stop when a red lamp R is illuminated, and proceed with caution (or simply caution) when both a yellow lamp Y and a red lamp R are illuminated simultaneously.

Specification of Letters Patent.

Patented Mar. 30, 1920.

Serial No. 170,427.

The red and green signal lamps are con trolled by signal relay P located adjacent thereto. These relays may be energized in a normal or reverse direction in a manner which I shall explain hereinafter. When these relays are de'elnergized, their contact fingers 9, 10, 11 and 12 hang in a vertical position as indicated in the drawing; when the relays are energized in what I shall term the normal direction, these fingers swing in the direction of arrows N; and when they are energized in the reverse direction the contact fingers swing in the direction of arrows R. The control by relays P, of the circuits for the red and green lamps of the adjacent signals S is eiiected by contact fingers 11. Thus red light R of signal S is controlled by finger 11 of relay P by means of the following circuit: from terminal x of transformer T, through wires 13 and 14, contact finger 11 of relay 1 wire 18, red lamp R, wire 16, back contact 1? of track relay R, wires 81, 6 and 5 to terminal y of transformer T. To close the above circuit, relay P must be deenergized or energized reversely. If the relay is energized normally, it closes the circuit of the green lamp instead of the red lamp, current then flowing to lamp G through wire 15; otherwise thecircuit is the same as that of the red lamp. It will be noted that both of these circuits are normally open at contact 17 of track relay R I-Ience, both lamps are normally extinguished, and only while a car is approaching the signal is one or the other of the lamps illuminated, according to the position ofthe signal relay.

Each signal relay is controlled by the absence and presence, as well as by the phase relations of the currents in the windings m and n. Winding m of each relay is constantly energized, being directly connected to a source of current; for example, winding m. of relay P is energized through the circuit: from terminal 2 of transformer T, through wire 8, winding m of relay P, wires 7. 6 and 5 tovterminal y of transformer T. The winding a of each signal relay is connected in series with the corresponding winding of the signal relay at the other end of the block by means of a line wire 20 as I shall describe. in detail hereinafter.-

terminal g of transformer T which is at the same potential as terminal y of transformer T, being connected thereto by wire 28. lVith no current through windings a, the relays P are normally deenergizcd so that their contact fingers hang in the middle position, as shown in the drawing. However, when a train approaches the track section it operates a track relay to connect one end of this line circuit to a source of differout potential, either higher or lower, according to the direction of approach, so that current is sent through the winding 91 of the two signal relays in one direction or the other relative to the direction of the current through windings m so that the relays are energized in either the normal or the reverse direction for the purpose of control ling the signals as previously explained. To illustrate, when relay li is deenergized (as by the approach of a car or train to the track section BC) it opens contact 24 and closes contact 30, shifting thereby the connection of the left end of the line circuit from terminal y to terminal 03 of transformer T. This establishes the following circuit: from terminal a" of transformer T, through wire 13 and 31, contact 10 of relay P, wires 32, contact finger 33, wire 34, contact 30 of relay E wire 23, winding a of relay P, wire 22, contact 21 of relay R, wire 20, contact 21 of relay R wire 22, winding 9% of relay P wire 23, contact 24 of relay R wires 25, 81, 6, 28 and 5 to the middle terminal y of transformer T The direction of this current is normal. with respect to the current in winding m of relay P but reversed with respect to the current in winding m of relay P so that the contact fingers of relay P are thrown in the direction of arrow N and those of relay P are thrown in direction of arrow B. Consequently, signal S is caused to display a green light, permitting the eastbound car or train to enter block B'C Similarly, when relay R is deiinergized (as by the approach of a car or train to section BC from the east), it connects.

the right end of the line circuit to terminal a" of transformers T so that current flows through the line circuit in the opposite direction. Then relay P is energized normally and relay P is reversed, so that signal S displays the green light. Thus it is apparent that with the apparatus thus far c escribed, the car or train which first approaches a track section is allowed to enter the section.

It is desirable to allow a following car or train to proceed through the section-behind the first one. For this purpose I provide the yellow signal lamps hereinbefore mentioned, which are controlled by what I shall term the caution relays M, one of which is provided for the two signals at the end of each section. These relays comprise three windings 1", s, and s, of which winding 71 is constantly energized, being directly connected to the erminals of transformers T by wires 13 and 8. Only one of the other two windings is energized at one time. Winding s of relay M may be ener ized by current in the following circuit: Irom terminal 3 of transformer T, through wires 5, 6, 4-0 and 41, windings of relay M, wire 42, contact 43 of relay R, wire 44, contact 12 of relay P, wires 45 and 8, to terminal 2 of transformer T. 'lVinding 8: may be energized through a similar circuit controlled by relays P and R When winding s is energized the relay contact fingers swing to the right and when winding 8 is energized the relay contacts swing to the left. In the former case the relay closes at contact finger the circuit for yellow lamp Y of signal S which is as follows: from terminal 2 of transformer T, through wires 8. and 52, contactfiO of relay M, wire 53, yellow lamp Y, wire 16, contact 17 of relay it, wires 81, (land 5 to terminal 2 of trans former T. When energized to the left the relay M causes the illumination of yellow lamp Y of signal S in a similar manner. Thus one relay is used for the control of two signals, an important economical feature.

The above described energizing circuits for relays M are closed only temporarily, as will appear in the description of the operation. of the system; once the relays have been energized their contacts are held closed through a holding circuit, of which there are two for each relay, one for each direction of energization. For relay l the holding circuit for the s winding is as follows: from terminal. 2 of transformer T, through wires 8 and 45, contactfinger 12 of relay P, wire contact finger 61, 'wire 62, winding 8 of relay M, wires ll, 40, 6 and 5 to terminal 11 of transformer T. The holding circuit for the s winding is similar.

The operation of the system isas follows: While there is no car or train in the stretch, all the track relays are energized so that all signal lights are extinguished, because the circuits for these lights lead over back con tacts of the track relays, as hereinbefore' described. Furthermore, there is no flow of current in the line circuits as hereinbeforc explained and the line relays are therefore denergized, as are also the caution relays.

All parts ofthe apparatus are thereforerin the positions shown inthe drawing.

WVhen a car or train, passing through the stretch, approaches section 13 C from the west, it de'nergizes track relay R As hereinbefore explained this causes current of what Ihave termed normal polarity to flow in the line circuit of -sectioniB-C, and relay P is energized normally while relay I is energized reversely. Contact finger 11 of relay P therefore completes the circuit of green lightG, so *that the-signal S gives a proceed indication permitting the car or train to enter the section.

In order that the line circuit will not be broken by a westbound car or train ap- 'proaehing section B-eC and opening relay R, I provide'a branch around contact 24 of this relay, this branch comprising: wire 90, contact 9 of relay P and wire 91. This branch is not closed until relay P has been energized 'reversely, and remains closed until the line circuit is interrupted at another point.

lVhen the car or train enters section 'BC, track relay R opens the line circuit at contact 21, thus deenergizing signalrelays P and P -Before relay P can open its contacts, however, track relay R has closed its back contact 43 so that the energizingeircuit for winding -8 oifcaution relay M is completed through contact 12 of relay 5? "for a sufficiently long time to cause the relay M :toclose its right contacts. Immediately ai'ter this energizing circuit is broken at contact 12 of relay P, the holding circuit for windings of the caution relay is closed "through contact finger 12 of relay P and contact finger 61 of relay M. Thus the contact 50 of the caution relay is closed to the right with the result that the yellow "lamp of signal S is illuminated as well as the red lamp when another car or train approaches section B-C from the west. In this manner the second car or train is permitted to enter section B-C but cautioned that there is another eastbound car or train in the same section.

As the first-mentioned ear or train 'proeeeds through section B-C, it deenergizes relay R which opens the line circuit at contact 21 so that this-circuit remains broken when the first track relay of the section, relay R, again closes its contacts. Relay R also closes contact 30 so that it energizes the line circuit of the next section"(of which I have shown only the part C-D) in the normal direction, thus causing *thesame operation of the relays and signals for that sectign, as I have just described for section B hen the entire car or train leaves section B-C, relay R is reen'ergized'so thatall parts of the aparatus are restored to the positions shown in the drawing, with the 6XC6ptlO11 OtE'16hy M. This relay remains line circuit is energized in one direction or.

the other by the approach of a car or train to section B- C from one direction or the other.

The passageof a carer train through the stretch fromeastto west is similar and-need therefore not be described. It remains to be noted that a car or train receivesa stop indication when it approaches a track section -=whose line circuit has already been energized in the reverse direction or which isoecupied by a car or traintraveling in the opposite direction. Thus, during the approach of an eastbound ear or train to section B C, relay P is energized reversely and during its passage therethrough this relay is 'deenergized. In either position, contact finger 11 of the relay closes the circuit for the red light of signal S so that a westbound car-or train approaching section B-G receives a stop indication and must take the siding adjacent signal S in order to permit theopposing traflic to pass.

Although I have herein shown and described only one form of apparatus embodying'iny invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is: v

1. In combination, a stretch of railway track, signals oppositely located along said stretch 'for governing traflic in both directions and adapted to indicate proceed, caution, and stop, a signal relay for each signal for controlling the proceed indication of the signal, means controlled by the, approach of a train to a signal in the direction governed by the signal, for energizing the corresponding signal relay to cause a proceed indication of the signal, means for controlling each signal relay by the presence or absence of a train in the section of track extending to the next signal governing traffic in the same direction, a caution relay for each pair of oppositely located signals for controlling the caution indications thereof, means for energizing the caution relay in one direction or the other when a car or train passes the signal location in one direction or the other, and means for holding the caution relay energized while the ear or train is in the section of track extending to the next signal governing trafiic in the same direction.

'2. In combination, a stretch of railway track divided into sections, signals located adjacent the junction of each two adjacent sections for governing traflie "through said sections in opposite directions from the signet]. locations, each signal being adapted to d 4 d 77 it 7, 1 t t 77 in icate procee cau 1on anc s 0p,

a signal relay for each signal responsive to absence and presence as well as reversal of current, means for controllmg the stop and proceed indications of the signals by the signal relays, a line circuit for each section including windings of the signal relays for the signals governing trafiic into the section from both directions, means for each section controlled by a car or train approaching the section from one direction or the other for sending current through said line circuit in one relative direction or the other, said windings of the signal relays being so connected in said circuit that the cur rent through one of them is in a normal direction and through the other in a reverse direction at the same time, means for each section controlled by a car or train in the section for opening the line circuit, a three-position relay for each pair of adjacently located signals for controlling the caution indications thereof, means for energizing said latter relay in one direction when a train enters the section governed by one of the signals, and for holding said relay closed in said direction while the car or train occupies the section, and means for energizing the latter relay in the other direction when a train enters the section governed by the other signal and for holding the latter relay closed in said'direction while the car or train occupies that section.

3. In combination, a stretch of. railway track divided into sections, track circuits comprising track relays for the sections, signals located adjacent the junction of each two adjacent sections for governing traflic through said sections in opposite dir ctions from the signal locations, said signals having three indications, namely, proceed, caution, and stop, a signal relay for each signal adapted to be energized in a normal or a reverse direction, means for controlling the proceed and stop indications of the signals by said signal relays, a circuit for each section including energizing windings of the signal relays at the ends of thesection, means for controlling the circuit of each section by the track relays of the section, means controlled by track relays of the adjacent sections for sending through said circuit current of one relative direction or the other, the windings of said signal relays being so connected into said circuit that the current through one of them is in a normal direction and through the other in a reverse direction at the same time, a cantion relay for each two adjacently located signals for controlling the caution indications thereof, means for each caution relay for energizingthe relay in one direction controlled by the signal relay for'one of the signals controlled by the caution relay, and

by the track relay first opened by a train passing into the section governed 'by that signal, means for holding said caution relay energized in said direction controlled by said signal relay and by a contact of the caution relay, means for energizing the cantion relay in the opposite direction controlled by the signal relay for the other signal and the track relay first opened by a train passing into the section governed by the said signal, and means for holding said caution relay energized in said opposite direction controlled by the last mentioned signal relay and by a contact of the caution relay. 7

l. In combination, a stretch of railway track, two signals located ator near one point for governing traflic in opposite directions from such point, a relay having two windings and two contacts, one or the other of said contacts being closed according as one or the other of said windings is energized, means for controlling said two signals by said two contacts respectively, and means controlled by a car or train passing along said track for energizing one or the other of said relay windings according as said car or train is moving in one'direction or the other. a 5

5. In combination, a stretch of railway track, two signals located at or near one point and governing traffic in opposite directions from such point; a relay having a main winding constantly energized, two auxiliary windings, and two contacts, one contact or the other being closed according as one auxiliary winding or the other is energized, circuits for said two signals controlled by said two contacts respectively, and means controlled by cars or trains passing along said track for energizing one or the other of said auxiliary windings according ,to the direction in which the car or train is moving.

6. In combination, a .stretch of railway track, two signals located at or near one point and governing trafiic in opposite directions from such point; a relay having an armature biased to an intermediate position and movable in one direction or the other therefrom according as the relay is energized in one direction or the other, two contacts 7 one or the other of which is closed according in which the car or train is moving.

'7. In combination, a stretch of railway track, two signals located at or near one point and governing traflic in opposite directions from such point; each signal; being adapted to indicate stop, caution or proceed, a relay having two contacts one or the other of which is closed according as the relay is energized in one direction or the other, caution circuits one for each signal and controlled respectively by said two contacts, and means controlled by cars or trains for governing the stop and proceed indications of said signals and for energizing said relay in one direction or the other according to the direction in which the car or train is moving.

8. In combination, a stretch of railway track divided into sections, two signals located adjacent each junction 01": adjacentsections for governing traflic through said two sections respectively from said junction, a signal relay for each signal responsive to reversals of current and to the presence and absence of current, means for causing each signal to indicate proceed when the corresponding signal relay is energized in normal direction; and stop when the relay is energized in reverse direction or deenergized, means for each section controlled by a train approachingthe section for energizing the signal relays for the two signals governing tratfic through the section, the relay for the signal governing traffic in the direction in which the train is moving being energized in normal direction and the other relay in reverse direction, means for each section for denergizing the signal relays for the signals governing trafiic through the section when the section is occupied, a caution relay for each pair of adjacent signals, means con trolled by each caution relay for causing one or the other of the corresponding signals to indicate caution according as the relay is energized in one direction or the other, means controlled by a train entering a section for energizing the caution relay at the entering end in such direction as to cause the signal governing trafiic through the section in the direction of movement of the train to indicate caution, and means for keeping such caution relay energized in said direction as long as the train occupies such section.

In testimony whereof, I a'ffix my signature in presence of two witnesses.

RONALD A. MoCANN.

Witnesses A. C. NoLrE, CHAS. H. LAY. 

